A slide fastener is an opening and closing device for an article utilized in not only daily necessities such as clothing, bags, shoes and general merchandise but also in industrial goods such as a water tank, a fishing net and a space suit.
In FIG. 1, the constitution of a typical slide fastener is shown, and the slide fastener 10 is mainly composed of three parts: a pair of long tapes 11, a number of elements 12 which are engaging parts of the fastener sewn on along one side edge of each tape, and a slider 13 to control opening and closing of the fastener by engaging and separating the elements 12. In addition, a top end stop 14 and an opening device 15 can be provided to prevent dropping off of the slider 13, and a pull tab 16 can be attached on the front face of the slider 13. The opening device 15 can be composed of an insert pin 15a and a box body 15c with a box pin 15b. The slider 13 releases engagement between elements 12, while being moved to the opening device 15 provided at the bottom portion of the long tapes 11, and then, the insert pin 15a is pulled out from the box body 15c to separate each tape 11.
The slider composing a slide fastener is a molded component capable of being manufactured by means of injection molding, and it is known that the slider can be manufactured using polyamide as a material.
For example, DE3444813 (Patent Literature 1) describes a method (Claim 1) for injection molding a slider by using as a material a polyamide reinforced with glass fiber, for the purpose of improving the durability against washing and ironing of sliders used for slide fasteners for bedclothes and the abrasion resistance against sliding of sliders. The length of the glass fiber is described to be 4 to 8 mm, and the content of the glass fiber is described to be 25% by weight or more (Claim 1). The slider is described to be subjected to a recrystallization treatment after molding (Claim 1). Polyamide 6, 6 is described to be used as the polyamide (Claim 6). It is also described that a polyamide containing neither a lubricant nor a gliding agent is used, and the content of glass fiber is approximately 40% by weight (Claim 5).
Japanese Patent No. 4517277 (Patent Literature 2) also describes the usability of a polyamide resin as components for slide fasteners. In the patent literature concerned, examples of the polyamide resin include polyamide 6, polyamide 66, polyamide MXD6, polyamide 6T, polyamide 11 and polyamide 12. In particular, a polyamide resin having the carpamide repeating unit in a content of 80 mol % or more and/or a polyamide resin having the hexamethyleneadipamide repeating unit in a content of 80 mol % or more is described as preferable.
WO2013/098978 (Patent Literature 3) discloses a polyamide resin composition including 30 to 50% by mass of a polyamide and 50 to 70% by mass of reinforcing fiber wherein 50% by mass or more of the polyamide is an aliphatic polyamide. As described in the patent literature concerned, the content of the aliphatic polyamide in the polyamide is preferably 80% by mass or more, from the viewpoint of the improvement of the platability.